In the prior art, it is known to provide colostomy and ileostomy patients with a waterproof, odorproof container or pouch to collect their intestinal discharge from surgically created stoma. Typically, these containers comprise a flat, flexible plastic bag, with an opening positioned over the patient's stoma. The bag is attached to the peri-stomal skin by an adhesive. FIG. 1 shows a typical ostomy bag designated by the reference numeral 10 and including a plastic film pouch 1, stomal opening 3, and an adhesive skin barrier 5 for attachment to a patient.
In some types of prior art bags, the bags were air tight which caused problems if a patient produced moderate or large amounts of bowel gas. This bowel gas can develop into a large bulge over the abdomen which can be embarrassing and uncomfortable to a user. In addition, and as additional gas accumulates, pressure within the bag rises causing the skin-adhesive-bag interface to separate, leading to external leakage.
To overcome these problems, the prior art bags incorporate an odor absorbing gas filter 7 into the wall of the bag so that gas can be vented outside of the bag (see FIG. 1). These filter devices work well when the intestinal discharge is solid so that the filter remains dry. However, if the filter becomes wet, it will transmit liquid intestinal contents to the exterior of the bag causing soiling of clothes and/or skin. These types of filters also stop functioning as a filter when the filter media, usually charcoal, becomes wet through contact with liquid contained within the plastic bag.
As can be seen from FIG. 1, the filters are usually located at the upper end of the ostomy bag and depend on gravity for separation of solids from gas. Typically, the gas rises to and through the filter with the liquid and/or solid material flowing downwardly. However, this separation process is usually unsuccessful when more than a few cubic centimeters of liquid are produced. The bag is constructed to have a generally flat profile and the bag sides are held in opposition by the design of the bag as well as compression of the bag between external clothing and the abdominal wall. The failure of the liquid and gas separation when more than a few cubic centimeters of liquid are produced is caused by the capillary action of the opposing sides of the flexible plastic bag. This results in the fluid within the bag being layered in a generally vertical direction, rather than collecting in the dependent or lower parts, resulting in liquid being drawn up through the filter to the outside of the bag. Under these conditions, the filter contributes to leakage by acting as a wick.
In view of the disadvantages and deficiencies of the prior art as explained above, a need has developed to provide an improved ostomy bag which overcomes the problems of liquid-gas separation and leakage of liquid through the bag filter.
The prior art has proposed collection pouches for use by ostomates to facilitate extended use of a pouch. U.S. Pat. No. 4,411,659 to Jensen teaches a barrier plastic film to shield the filter from exudate. However, this construction still fails to overcome the problem of fluid contacting and being drawn through the filter.
It is also known to use filtered stoma caps such as the one shown in exploded view depicted in FIG. 2 and generally designated as reference numeral 20. These stoma caps, one type manufactured by Convatec, include a perforated plastic cover 9, charcoal filter 11, and an absorbent backing 13 placed over the stomal opening 15 in the plastic film pouch 17. These devices function as a filter only and do not function well where more than a trace, e.g. 1 or 2 cc's, of intestinal contents is produced. Once the backing 13 becomes wet, the stoma filter has no capacity for solid or liquid storage. In fact, the backing actually draws liquid into the filter, rather than diverting it, further contributing to non-functionality.
In response to the disadvantages of the prior art as described above, the present invention provides an ostomy bag or pouch which can be worn for an extended period of time prior to changing through improved gas-liquid separation.